Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China.
Carbohydr Polym. 2014 Jan 30;101:272-80. doi: 10.1016/j.carbpol.2013.08.085. Epub 2013 Sep 12.
Novel hydrogels were prepared from hemicelluloses, polyvinyl alcohol (PVA), and chitin nanowhiskers through 0, 1, 3, 5, 7, and 9 times of freeze/thaw cycle. These hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), swelling property, and compressive strength. The repeated freeze/thaw cycles induced physically crosslinked chains packing among these polymers, and a phase separation caused by the hydrogen bonds. Larger pores led to a high swelling degree, whereas the formation of compact structure after multiple freeze/thaw cycles resulted in high mechanical strength and thermal stability. The highest compressive strength of these hydrogels was achieved by the 9 times of freeze/thaw cycles with compressive stress of 10.5 MPa. This work provides a remarkable way for the preparation of hydrogels with good mechanical properties by physical method.
新型水凝胶由半纤维素、聚乙烯醇（PVA）和壳聚糖纳米纤维通过 0、1、3、5、7 和 9 次冻融循环制备而成。这些水凝胶通过傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、X 射线衍射（XRD）、热重分析（TGA）、溶胀性能和压缩强度进行了表征。重复的冻融循环诱导了这些聚合物之间的物理交联链的组装，以及氢键引起的相分离。较大的孔导致高溶胀度，而多次冻融循环后形成的紧密结构导致高机械强度和热稳定性。这些水凝胶的最高压缩强度是通过 9 次冻融循环获得的，压缩应力为 10.5 MPa。这项工作为通过物理方法制备具有良好机械性能的水凝胶提供了一种显著的方法。
